"In spring this year my life changed massively when I met someone, and they make me feel so happy, so safe and everything just feels great," Daley told fans. "That someone is a guy."

Thomas was one of the first celebrities to applaud the teen for taking the brave step.

"When the dust settles Tom Daley will realise today is the start of an amazing life. Congratulations," he tweeted.

Thomas, who credits his "great life" to his decision to come out as gay in 2009, told the Mirror that Daley would soon understand the magnitude of his courage.

"Tom will empower thousands of other people. It's a huge achievement," Thomas said. "Whatever Tom Daley achieves, there will come a time when he looks back on today and realises it was the best day of his life.

"I was in his position. Now I am deeply in love with my partner. We can walk down the street hand in hand and I can introduce him as my partner."

He continued: "These are simple things but they become such a massive deal for someone hiding their sexuality. My life is great and it all stems from the day I told people the truth.

"I felt humbled when I watched Tom's video. He did it in such a personal way to millions of people."

Thomas also revealed that he struggled to keep up the charade during his nine-year marriage to Jemma Thomas and constantly contemplated suicide.

He said: "Before I came out I tried to kill myself on many occasions. I was lying to so many people and they were getting hurt by my lies until I hated myself.

"I told my family two years before I publicly came out. I was married at the time and so I told my wife and my closest family and friends. With their support I found the strength to tell the world.

After coming out, Thomas transitioned from sports to television and showbiz and made appearances on reality shows including Celebrity Big Brother.

"My main feeling was fear - fear about the backlash, about whether people would accept me and how my family would be perceived, because it was a huge thing for them too. But there was also relief," he said.

"Tom will be relieved as well. He doesn't have to operate within the shadows now, wondering what people are saying behind his back."